Gaffer Tape said:

Xhonzi's logic is sound...

Thanks!

However, if you're genuinely buying it used, as in buying it from someone who originally bought it and then decided to no longer have it, then that's a different story. You're not creating any more demand the product. You're simply creating a situation wherein one unique copy is being effectively shared between two or more people, when it would previously have only been meant for one.

Except you ARE still lowering supply. If you buy it, someone else can't. It doesn't have the same effect that buying it new would, but it will still have some effect. You're increasing the "final destinations" for the BD by 1.

You're not creating a new middleman.

And I'm not sure what you mean by saying that there isn't a new middleman. In my post, I meant that the eBay seller is yet another middle man. Maybe a new one, maybe not. I don't think it matters.

Also, consider this: The fewer people buying on eBay (and the same number of Discs available) would generally mean lower bids. The lower the price eBay copies are going for, the more competition there will be for the B&M or Online sellers, the lower the "new" prices will drop, the lower returns that retailers will earn, the less happy they'll be with stocking the item in the first place.